Air pollution damages human health and the environment. Considerable progress has been made in Europe to reduce emissions and exposure to different air pollutants such as sulphur dioxide (SO2) and lead (Pb). However, despite reductions, certain air pollutants, especially particulate matter (PM), ozone (O3), nitrogen dioxide (NO2) and some organic compounds, still pose a threat to human health. For the EEA-32 group of countries, it has been estimated that in 2005 almost 5 million lost life years could be attributed to air pollution with fine particles (PM2.5) alone.

As the amounts of acidifying air pollutants have fallen, the area of acid-sensitive ecosystems (such as freshwaters and forest soils) adversely affected in Europe has considerably reduced. Nonetheless, biological recovery in freshwaters is slow. The area of sensitive terrestrial and freshwater ecosystems affected by an excess input of atmospheric nitrogen in the EEA-32 has only diminished slightly between 1990 and 2010. The EU’s long-term objective of not exceeding the so-called critical atmospheric pollutant loads, which ecosystems can tolerate, has not been met.

European air pollutant concentrations still frequently exceed limit values set by the EU Air Quality Directives. Many Member States have either not complied, or will not comply by the required target dates, with legally-binding air quality limits set for the protection of human health. Examples are the 2005 limit value for particulate matter (PM10) and the 2010 limit value for nitrogen dioxide (NO2). Exposures of agricultural crops and other vegetation to ground-level ozone (O3) also continue to exceed the EU’s long-term objectives.

Only 14 European countries expect to comply with national 2010 emission ceilings for four pollutants (NOx, NMVOC, SO2 and NH3) set under EU and international legislation. The ceiling for nitrogen oxides (NOx) remains by far the most difficult for many countries to meet – 12 countries estimate they will exceed the ceiling, in some cases significantly, by up to 50 %.

As European emissions decrease, there is increasing recognition of the importance of inter-continental transport of air pollutants and its contribution to poor air quality in Europe. This contribution is particularly large for ozone, persistent organic pollutants, and mercury, and for particulate matter during air pollution episodes. Further international cooperation to mitigate inter-continental flows of air pollution will help nations meet their own goals and objectives for protecting public health and environmental quality.

Air pollution and climate change share common sources of emissions – primarily from fuel combustion in industry and households, transport and agriculture. A number of air pollutants contribute to changes in atmospheric radiative forcing. Many climate change mitigation policies are positive in terms of also improving air quality. Factoring air quality into decisions about how to reach climate change targets, and vice versa, results in policies with greater benefits to society.

Emissions of air pollutants derive from almost all economic and societal activities. They result
in clear risks to human health and ecosystems. In Europe, policies and actions at all levels have
greatly reduced anthropogenic emissions and exposure but some air pollutants still harm human
health. Similarly, as emissions of acidifying pollutants have reduced, the situation for Europe's rivers
and lakes has improved but atmospheric nitrogen oversupply still threatens biodiversity in sensitive
terrestrial and water ecosystems. The movement of atmospheric pollution between continents
attracts increasing political attention. Greater international cooperation, also focusing on links
between climate and air pollution policies, is required more than ever to address air pollution.

Human activities are the main cause of poor air quality, but natural sources of air pollution also play a role. The most common natural sources of particulate matter in Europe are desert dust, volcanoes, forest and grassland fires, and salt from sea spray